“We’ll be remembered as a good band if we don’t turn into idiots,” he told a Nottingham cinema audience after a recent screening of a new documentary, Bunch of Kunst, which charts the recording of their album Key Markets in 2015.

Since then Williamson, a former benefits adviser, and musical cohort Andrew Fearn, have written and recorded another album – English Tapas, which was released to rave reviews in March.

The film shows the pair recording at Nottingham’s Rubber Biscuit studios and offers glimpses of their creative partnership with deadpan exchanges typical of their offbeat and unaffected style:

“D’ya get what I’m saying?”

“No, not really.”

As Williamson recites rants he’s written on to his phone, Fearn plays sparse electonica and bobs his head in time to the beats issuing from his lap top, then complains about the faulty heaters in the draughty studio.

On a tour of unpromising venues across small-town England, Fearn and Williamson are driven by manager Steve Underwood, the mastermind of a record label which released 120 discs before he gave the Mods a chance.

Although the duo have had the mantle of political spokespeople thrust upon them, the film leaves direct polemic to one side.

Williamson’s angry, often hilarious, and sometimes touching tirades about “dead-end jobs and the feeling you are slipping through the cracks in society” are summed up best by Fearn as “awesome poetry.”

“You do get blown away by how he does it,” he tells the camera.

Then, Williamson’s father offers a cheerfully obscene estimation of his son’s character.

Later, they climb aboard a Jumbocruiser, for storming shows at Glastonbury, a triumphant gig at Rock City in Nottingham, and a support slot with the Libertines at the O2 Arena.

But as Williamson drily notes: “You don’t get too affected by it. We’re a bit too long in the tooth.”

After a show in Huddersfield one fan says: “The music feels like it’s been written with you in mind. That’s the most amazing thing.”

A 54-year old woman in Newcastle says: “The best gig I have seen since the Sex Pistols in 1976.”

Another youth says: “It’s music for the people.”

This funny, affectionate and unexcitable film captures a year in the life of a talented and self-deprecating pair of extremely unusual musicians, and finishes as they sign a one-off deal with legendary indie label Rough Trade.

Several years of persistent hard graft – and a prolific stream of records – are starting to pay off.

A Bunch of Kunst (German for art), directed by Christine Franz, will be showing at the Broadway Cinema in Nottingham.